Electrical plug



A. M.. WILLIAMS 2,448,339 ELECTRICAL PLUG Filed Jan "7, 1944 INVENTOR Patented Aug. 31, 1948 UNITED STATES PTENT OFFICE Alexander M. Williams, Watertown, S. Dak.

Application January 7, 1944, Serial No. 517A)? 1 Claim. 1

This invention relates to electrical plugs.

Where it is desired to energize several electrical devices or appliances by plugging into a single outlet connection, it is the common practice to use a special connection plug having a single set of prongs insertable into the outlet connection and provided with a plurality of sets of slots in which are respectively in-sertable the plugs carried by the cords of the various appliances. The special plugs referred to are unsightly and clumsy and usually require insertion of the cord plugs at various angles.

An important object of the present invention is to provide a novel simple type of connection plug which may be used as standard equipment on all appliances and of such novel character as to permit the plugging in of the successive plugs of different appliance one on top of another without making a clumsy arrangement of plugs.

A further object is to provide a plug of this character which is exceptionally compact to minimize the projection from a wall of several of the plugs successively inserted in each other.

A further object is to provide such a plug wherein the insertable contacts projecting from each plug serve also as contacts receiving those of the next successive plug.

A further object is to provide a novel type of contact doubled back upon itself so that the projecting end of each contact firmly engages the contacts into which it is inserted, and which firmly engages each contact of the next successive plug and is expanded thereby to be more tightly held in position.

A further object is to provide a plug of the type referred to wherein the arrangement of parts is such that a succession of plugs, if desired, may be permanently bolted together as a single unit.

A further object is to provide, in combination with the type of plug referred to, a cover plate to positively close the openings of the last plug to prevent dirt or any foreign material from lodging in the contact openings, etc.

A further object is to provide a device of this character wherein each plug is provided at a readily accessible point with its own individual switch whereby any appliance can be cut out of operation without affecting the other appliances.

Other objects and advantages of the invention will become apparent from the following description.

In the drawing I have shown one embodiment of the invention. In this showing Figure 1 is a perspective view of one type of plus,

Figure 2 is a bottom plan view of the same showing the cover disk removed,

(Cl. ZOO-51.02)

Figure 3 is a transverse sectional view on line 3--3 of Figure 2,

Figure 4 is an enlarged detail perspective View of the pair of contact elements employed with the plug,

Figure 5 i a longitudinal sectional view through one of the contact elements,

Figure 6 is a perspective view of a cover plate adapted for use in connection with the device,

Figure '7 is a bottom plan view similar to Figure 2 showing a, modified form of the device,

Figure 8 is a similar view showing a further modification,

Figure 9 is a transverse sectional view on line El-Q of Figure 8, and,

Figure 10 is a plan View showing the arrangement of a plurality of the devices shown in Figures 1 and 7 as they would appear superimposed and in electrical engagement with a wall unit.

Referring to Figures 1 to 5 inclusive, the numeral l0 designates the body of the plug formed of insulating material and having an outstanding preferably milled flange II for convenience in inserting and removing the plug. As shown in Figure 3 the plug is formed with a head 12 of the edge of which the flange l I is a continuation, and this head is formed integral with a cylindrical flange or skirt IS. The head !2 is provided with parallel prong receiving openings M and a central opening H: for the reception of a bolt or screw for securing together a number of the plugs as will become apparent.

A pair of contact elements I6 of the type shown in Figures 4 and 5 are arranged in the skirt I3. The contacts l6 may be identical and as clearly shown in Figure 5 each contact is bent upon itself as at ll to form integral spaced and slightly diverging contact strips 18 one of which is bent directly outwardly as at [9 and apertured asat 20 to receive a fastening screw 2| (Figure 2) for holding the adjacent strip I8 fixed with respect to the head It. The other contact strip I8 of each pair is bent outwardly as at 22 in the plane of the bent end l9 and is extended laterally with respect to the alinement of the two contacts I6 and terminates in an enlargement 23 apertured as at 24 to receive a screw 25 by means of which it is secured to the head 12. Adjacent the bend H of each contact unit IS the strips l8 thereof are apertured as at 26 (Figures 4 and 5) and above such apertures each strip i8 is punched inwardly as at 21. This provides each strip IS with an inwardly extending knob which will be received in the openings 26 of the next following contact l6, as will become apparent.

It will be apparent that the contact units 16 of each plug extend beyond the open end of the skirt I3 to be inserted through the openings [4 of an adjacent plug tobe engaged between thestrips l8 of such adjacent plug. The open end of each plug is covered by a fiber disk 28 (Figure 1) which is conventional, this disk being apertured for the extension therethrough of the contact units IS. The skirt I3 is notched as at 29 for the reception of the lead wires extending into the plug. The disk 28 forms one wall of the opening defined by the notch 29 as will be apparent. lines in Figure 2 and is designated. by, the nu, meral 30. The two individual wires thereofare connected to the respective. contacts; by; thescrews 25, these screws being somewhat larger than the screws 2| and serving as bindingposts:

It will be apparent that a succession of the plugs-referred to may beconnected together with the prongs or contacts l6 of the first plug inserted into a conventional convenienceoutlet indicated generallyin Figure by the numeral 3|. The outermost plug may be covered-by a plate or disk 32 (Figure 6) which is'preferably molded of hard'insulating material and provided with projections 33insertab1e inthe openings 14 of the outermostplug. The projections 33 may-be of? any desiredmaterial and if formed of metal, they may be secured to the plate 33. in any suita-- ble manner so long as they are electrically disconnected as will be obvious. The. plate 32 is provided with an axial opening 3'4 to'receive a bolt the head of which is indicated-by the numeral 35' in Figure 10. Such boiti may extend through the openings [5 of the various plugs for securing them together as a unit..

In the'form of theinvention'previously described the plug is circular in: form and the binding posts-25 are arrangedat opposite sides Accordingly the respective lead of the plug. wires Will extend throughthe notch 29:a'nd1one will be directly connected'to theadjacent bind ing post zdwhile the other willextendcacross the plug as shown indotted lines -in Figure 2ito: be attachedto the other binding post1125. If both binding posts are desiredto bexarrangediat the same side of the plug the form of the invention shown in Figure 7 may be employed. In" this form ofthe invention the plug may be'g'enera-llys rectangularin shape, the'body ofthe plug being.

indicated by'the numerali36. The plugbody. in

cross-sectionwill be substantially. identical with. the plugshown in Figure 3; In ltheformof .the: invention shown in-Figure .7 the twocontact unitsl6 will be the reverse of each other as will'be obvious. Except for the portion to.whlch the wires are connected, eachof-the contact units.

lB'will b'e identica'lwith those previouslydescribed. Instead'of having the enlargements 23 turned inwardly toward thecenter of the plug and provided with the binding post 25-.-

distance apart;

In the form of'the invention shown in Figures 8 and 9 an elongated'plug'body isflis employed to provide for a switch to. cut'ofi' the electrical appliance connected to the plug. In the form ofthe invention shown "in Figure-8' eachof 'thestrips" wardly as at 39, similar to the turned-end l9" previously described. Each endof each contact is provided with anatt'aching; screw the inner of I which, indicated by the numeral40, may: be relatively small and the outer of which; indicated 'by The lead wire is indicated bydotted:

the numeral 4|, may be somewhat larger to serve as a binding post. One of these binding posts is directly connected by a wire 42 to a binding.,,post.43. in the. remote. end. of the plug. The other binding post 4| is connected'by 'a wire 44 to the binding post 45 of a switch contact 46. This contact is engageable by a switch arm 41 pivoted to the plug as at 48.

The switch arm 41 is shown in Figure 8 in engagement with the contact 46 and is movable into engagement with a stop 49 which may be formedintegra-lwith the top of the plug body. A snap-over spring 49 has electrical and mechanical'connection with a binding post 50 and is engaged over a projection 5| carried by the switch arm 4-1" at' the side thereof opposite the arm-41a Accordingly the spring 49"will holdthe switch arm 41' in engagement with either the contact 46 or stop 49.

Referring to. Figures -8' and 9 the numeral 52 indicates an operating" rod for the switch arm 41. These' two el'ements have: notched-engagement with each other as shown in 'Figure 9" and the rod 5-2 slides in' openings 53 i formedf ina the side walls of 'the'plug; The'rod 52 obviously-may be pushed backaand'forth to open and closed position.

The operation of the form ofthe device shown in Figures-1'to 5 inclusive will be obvious: from the foregoing description. Each contact unit l6 will be formed" of resilient material and when the projecting portions or? prongsofeach con tact unit are inserted intosa wall' outlet these. prongswill'function in the same manner as conventional plug prongs. The prongs of the-next-I successive plug will "be inserted through the openings I42 and between. thecontact: strips l8" of the pairsassociated with thepreceding plug: The second plug will be pushed inwardly until the'base of the plugzor the closure element zfl contacts withthe-top of'the precedingplugi At such time, the openings 26 ofthe-secontt plug= will snap over the lugs .21 Iof thefirst plug to be: effectively heldzin position thereby. Itwill be apparent that the inserting of the second pli'ig tends to' spread the strips of the'precedingcpairs. l8-to.cause themto more tightlyhold'iwitl'iir'i their socketandiwillialso cause a relativelytight gripping action betweennthe'conta'ct units: lbiof: the two plugs which arezin' engagement; with": each other:. Thersame'is true withnrespect. to successive. plugs i as will be: obvious. The simple' construction of" the device permits:the plug 'to'. be:=ma'de relatively shallow as indicated inFigures e 1, 3 and 10 and accordingly a substantialnum b'er ofi'the =.plugs may: be inserted-i. one: err-:top of the other without making. axbulley SfiI'iBSiOfiFCOII nectlons as is true'withthe use: oftalspeciall-multie outlet connectingplug; inserted. intola wall socket. The assembly of the. present": plugsi. will; be: neat: and I compact and the structuralifeatures .of the contact units l6? causev the plugs: to 1 be held: in: firmengagement with each other. Any-tendency for the plugs -towork' loose or sag and destroy orimpair the proper electrical connection will be greatly minimized. If desired, a plurality offthe; plugs, particularly if they areto be-left permanently in position, maybe bolted together as" suggested in Figure 10.

So far as the pl-ug in" features: of the device- -is concerned, the operation of all ofthe forms-ct plug illustrated will be identical. The iorm'oflthe plug in Figures 1 and 2 is advantageous over the plug shown in Figure-7'-'only"because=it "is slightly smaller in outside-dimensions, although itis'noshallower in its axial depth. As stated, one of the lead wires must pass almost entirely across the device in Figure 2 for connection with the remote binding post 25, This is no particular disadvantage, but the arrangement shown in Figure 7 is preferred since both wires may be easily simultaneously cut and stripped the same length for connection with the binding posts 25 adjacent the inlet notch 29.

The form of the invention shown in Figure 8, while obviously slightly more expensive to manufacture .and somewhat bulkier, is of the same depth as the other forms of the device and is advantageous for the reason that it provides a separate cutofi switch for controlling each individual appliance without afiecting the others. The greater length of the plug in Figure 8 is slightly advantageous in that it further eliminates any tendency for the plugs to sag because of its substantial area.

The cover plate 32 may be employed in the form of the invention shown in Figures 1 to 5 inclusive to form a positive closure for the outermost plug. The same arrangement may be employed with the plugs shown in Figures 7 and 8 except that the plate 32 obviously will be shaped to correspond to the shape of the particular plug body.

It will be apparent that for economy in manufacture all of the plugs of a given type will be made identical with each other. However, if it is desired to extend the lead wires 30 of the several appliances in difierent directions, it will be apparent that the various plugs may be inserted 180 degrees with respect to each other. For example, in Figure 10 three of the lead wires 30 of dilferent appliances have been shown extending toward the right whereas one of the lead wires is shown turned 180 degrees with respect to the other lead wires to extend toward the left.

It is to be understood that the form of the invention herewith shown and described is to be taken as a preferred example of the same and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subioined claim.

I claim:

An electrical connection plug comprising a plug body having one wall provided with spaced parallel prong-receiving openings, a pair of contactelements connected to said body therewithin and having portions projecting from the side of said body opposite said openings, the projecting portions of said contact elements constituting prongs corresponding in arrangement to said openings, each of said contact elements comprising a pair of contact strips having their portions within said plug body forming contact sockets engageable with prongs inserted through said openings, said plug body having a hollow laterally projecting integral portion, a pair of binding posts carried by said projecting portion remote from said contact elements, and switch means within the projecting portion of said body for controlling electrical connection between said contact elements and said binding posts.

ALEXANDER M. WILLIAMS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,588,183 Goddard June 8, 1926 1,682,335 Hendry Aug. 28, 1928 1,728,549 Huppert Sept. 17, 1929 1,734,073 Canton et al Nov. 5, 1929 1,804,474 Martin May 12, 1931 1,917,909 Stryker July 11, 1933 1,979,958 Clark Nov. 6, 1934 2,027,447 Percy Jan. 14, 1936 2,141,790 Keddy et al Dec. 27, 1938 2,159,939 Chirelstein May 23, 1939 2,186,751 Chirelstein Jan. 9, 1940 FOREIGN PATENTS Number Country Date 208,056 Switzerland Mar. 16, 1940 

